But the simple act of going back to the past changes the past. I mean, you weren’t around in 1820, right? So it changed.

No. Let’s say that next year I’m going to travel back to 1820.

If it’s true that I will do that then it’s true that I was there.

Stephen

And that you got there from a time machine. But if you got there from a time machine, you weren’t there before using the time machine. See what I mean?

Imagine Jesus was a time traveler from the future who got there in a time machine.

If so he was there before using the time machine.

Stephen

Ok, now I am confused. Jesus (why pick him?) got to the past by using a time machine. But you said that he couldn’t have gotten to the past unless he had been in that past - so why need a time machine?

EDIT TO ADD: Wait, I see what you mean. But I also see that this version of time travel is sort of spooky in the sense that you would never be able to remember that you got back to this time via a machine.

Ok, I also saw what you meant after posting.

I get in the time machine in 2012 and go back to 1820. This takes three minute. so from my point of view time passes normally and so I can remember it. 1820 follows on from 2012 from my time traveling point of view.

Ok, now I am confused. Jesus (why pick him?) got to the past by using a time machine. But you said that he couldn’t have gotten to the past unless he had been in that past - so why need a time machine?

He got to the past and he was in the past. Just like we’ll get to the future and will be in the future.

Dunno why I picked Jesus.

Stephen

OK, when you say he got to the past and he was in the past… was he in the past even if he did not go back to the past? I was in the past, even though I won’t go back to the past. BUT, if I do go back to the past, then my knowledge of going back to the past, changes that past. This is what I meant when I said that going back to the past changes the past.

The past does not exist to go back to. Time is just our conceptualization of the changes in reality.

NOW is the position and vector of every atomic particle. Some “time” in the past consists of all of the positions and vectors of all of those particles then. But there is no point in the past to go back to because all of those particles are where they are now. Every atom in your body is millions of years old. They existed 1000 years ago. So if all of the atoms in your body went back to where they were 200 years ago then you would cease to exist.

psik

You cannot go back in time. The atoms in your body existed in the past. Those atoms cannot be in two positions at the same time. End of discussion.

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You cannot have a rational conversation with someone who holds irrational beliefs.

The past does not exist to go back to. Time is just our conceptualization of the changes in reality.

NOW is the position and vector of every atomic particle. Some “time” in the past consists of all of the positions and vectors of all of those particles then. But there is no point in the past to go back to because all of those particles are where they are now. Every atom in your body is millions of years old. They existed 1000 years ago. So if all of the atoms in your body went back to where they were 200 years ago then you would cease to exist.

psik

You cannot go back in time. The atoms in your body existed in the past. Those atoms cannot be in two positions at the same time. End of discussion.

There is nothing that ties these two sets of atoms together other than their history, so there’s no logical reason they couldn’t exist at the same time (assuming we found a way to time travel, of course).

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“What people do is they confuse cynicism with skepticism. Cynicism is ‘you can’t change anything, everything sucks, there’s no point to anything.’ Skepticism is, ‘well, I’m not so sure.’” -Bill Nye

To an observer we must look like one of those mechanical horseracing tracks. Each horse moves in little spurts relative to the other horses, gaining and losing time relative to each in the process, with an eventual winner who crosses the finish line slightly younger than all the other contestants, but also younger than the observer himself.

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Art is the creation of that which evokes an emotional response, leading to thoughts of the noblest kind.W4U

Hey, I’m a time traveler. I’ve traveled 81 years into the future since I was born 81 years ago.

Occam

I dare say that, if you have had occasion to actually travel a lot, you are either younger or you have traveled more than 81 years into the future relative to someone who has led a more sedentary life…

Yeah, it’s a bit crude traveler, but I get exasperated with people hijacking what should be a scientific discussion into philosophical solipsism. This thread should have ended with psikey’s post. Try as you might, you cannot get the same atoms to exist at different physical locations at the same time. The philosophical musings in this thread are wasted bandwidth, nothing more. Take it to the philosophy forum and I will happily ignore the discussion.

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You cannot have a rational conversation with someone who holds irrational beliefs.